| 主权项 |
1. A hydrocarbon conversion process, comprising:
(1) providing a first mixture comprising water and hydrocarbon, the hydrocarbon comprising ≧75.0 wt. % of alkane having two or three carbon atoms and mixtures thereof; (2) providing a pyrolysis furnace, the pyrolysis furnace comprising a radiant section comprising one or more radiant coils comprising at least one joined pyrolysis-furnace tube which comprises a first and a second pyrolysis-furnace tube, wherein
(a) the first pyrolysis-furnace tube, the first pyrolysis furnace tube having (i) an outer surface, (ii) an inner surface, (iii) first and second faces, and (iv) the inner surface having N fins, each fin comprising a fin tip adjacent to two fin roots, wherein (a) the outer surface and the fin roots are separated by an average distance t1, (b) each fin tip protrudes inward an average distance t2 from the fin root, (c) the first pyrolysis furnace tube comprises ≧33.0 wt. % chromium and ≧43.0 wt. % nickel, based on the weight of the first pyrolysis furnace tube, and (d) N≧6;(b) the second pyrolysis-furnace tube, the second pyrolysis furnace tube having (i) an outer surface, (ii) an inner surface, (iii) first and second faces, and (iv) the inner surface having N′ fins, each fin comprising a fin tip adjacent to two fin roots, wherein (a) the outer surface and the fin roots are separated by an average distance t1′, (b) each fin tip protrudes inward an average distance t2′ from the fin root, (c) the second pyrolysis furnace tube comprises ≧33.0 wt. % chromium and ≧43.0 wt. % nickel, based on the weight of the second pyrolysis furnace tube, and (d) N′≧6; and(c) a tube joint, the tube joint connecting the first and second pyrolysis furnace tubes and being open to the flow of the first mixture, wherein
(i) the second face of the first pyrolysis furnace tube is joined to the first face of the second pyrolysis-furnace tube, the second face of the first pyrolysis-furnace tube having substantially the same exterior cross-section as the second pyrolysis-furnace tube,(ii) the second face of the first pyrolysis tube has (a) a first counterbore extending away from the first face to a first location a distance L/2 into the first furnace tube, the first counterbore being a substantially uniform counterbore with L being in the range of from (t2/t1)·2.5 cm to (t2/t1)·12.7 cm, and (b) a second counterbore, the second counterbore being a substantially conical counterbore beginning at the first location and having a conical angle in the range of from 5.0° to 20.0°, and(iii) the first face of the second pyrolysis tube has (a) a first counterbore, the first counterbore being a substantially uniform counterbore extending away from the second face to a second location a distance L′/2 into the second furnace tube, with L′ being in the range of from (t2′/t1′)·2.5 cm to (t2′/t1′)·12.7 cm, and (b) a second counterbore, the second counterbore being a substantially conical counterbore beginning at the second location with the conical angle being in the range of from 5.0° to 20.0°; (3) conducting the first mixture through the at least one joined pyrolysis-furnace tube to expose the first mixture to a temperature ≧400° C. under pyrolysis conditions and convert at least a portion of the first mixture's alkane to C2 unsaturates; wherein the first mixture further comprises 0.20 to 1.0 weight of steam per weight of hydrocarbon and the pyrolysis conditions include one or more of: (i) a maximum hydrocarbon temperature in the range of 700° C. to 1100° C.; (ii) a pressure in the range of from 1.0 to 5.0 bar (absolute); and (iii) a residence time in the radiant coil in the range of from 0.10 to 2.0 seconds. |
